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How many lumens for a bathroom?

Quick answer

1,250–1,850 lumens for 5 m² · 100–150 lux

A bathroom 2.5 × 2 m (5 m²) needs 1,250–1,850 lumens from all its bulbs together, to reach 100–150 lux. Take about 70% from the ceiling and 30% from lights beside the mirror, where your face needs about 150 lux, at 3500–4500 K.

By the Snuug team · Updated · Worked out with the room lighting calculator

The light that matters most in a bathroom is the one at the mirror. A downlight straight above it throws shadows under the eyes and chin. A light on each side of the mirror, at face height, lights the face evenly.

Bathroom fittings are rated by how well they keep water out, and the rating you need depends on how close the fitting is to the bath or shower. Check it with an electrician before you buy: this page works out brightness only.

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To scale, from above: where downlights go if the ceiling light is all downlights. Each circle is a rough pool of light.

Worked out for A bathroom 2.5 × 2 m (8 ft 2 in × 6 ft 7 in), 5 m² of floor, with a 2.4 m (7 ft 10 in) ceiling and light walls. Change the numbers

The working

  1. Floor area = 2.5 × 2 = 5 m².
  2. Room index = 2.5 × 2 ÷ (1.6 × (2.5 + 2)) = 0.69, with 1.6 m from desk height to the ceiling.
  3. Utilisation factor = 0.3 + 0.15 × 0.69, kept between 0.35 and 0.65 = 0.4.
  4. Target 100–150 lux for a bathroom.
  5. Lumens = 100–150 × 5 ÷ 0.4 = 1,250–1,850 lm (rounded to 50).

These are targets for every light on at once. You will rarely run them all together, so fit dimmers.

The rules, and their sources

Light levels for each room

Lighting guidance from the Society of Light and Lighting (SLL) and CIBSE gives about 100–200 lux for a lounge, 50–100 lux for a bedroom, 150–300 lux for a kitchen, 100–150 lux for a bathroom, and 250–300 lux for a home office, with 500 lux at the desk.

An industry guideline Sources: Spear Lighting, Technical section: residential lux levels from SLL LG9 (2013), BS EN 12464-1 and HSG38; office lux levels (checked 31 October 2026); CIBSE, SLL LG9 Lighting for communal residential buildings (checked 31 October 2026); CIBSE Code for Interior Lighting (1994), hotel table as reproduced on SlideShare (checked 31 October 2026).

How much bulb light reaches the room

Only part of a bulb's lumens reach the floor and tables: about half in a typical room with light walls, less with dark walls, a high ceiling or a small room. Bulb lumens ≈ lux × floor area ÷ utilisation factor.

An industry guideline Source: electricaltechnology.org, Lighting design calculation in a building, step by step (checked 31 October 2026).

Light in layers

A rule designers use: light a room from at least two or three sources at two or more heights, not from one ceiling light.

A rule designers use Source: Emily Henderson, 19 lighting combos and rules (checked 15 October 2026).

Average room sizes in homes built since 2010

In LABC Warranty's 2018 analysis of 10,000 listings, the average living room in a home built since 2010 was 17.1 m², against 24.9 m² in the 1970s; the average bedroom was 13.4 m².

A published study Sources: Which? (Garber, 14 Apr 2018), Shrinking homes: the average British house is 20% smaller than in the 1970s (checked 31 October 2026); Statista, Average living room sizes in new British houses 1930–2020 (checked 31 October 2026).

Other rooms

The same sum for each kind of room. The living room, kitchen and bedroom are the average sizes in homes built in recent years; a bigger room or darker walls need more.

RoomAll bulbs togetherLight level
Living room4.5 × 3.8 m3,450–6,950 lumens100–200 lux
Living room4.5 × 3.8 m, dark walls4,350–8,700 lumens100–200 lux
Kitchen4 × 3.35 m4,250–8,550 lumens150–300 lux
Bedroom3.66 × 3.66 m1,400–2,850 lumens50–100 lux
Bathroom2.5 × 2 m this page1,250–1,850 lumens100–150 lux
Home office3 × 2.5 m4,400–5,250 lumens250–300 lux

Change the numbers

Your sizes will differ. The room lighting calculator opens with these numbers filled in: change any of them and the answer, the working and the drawing follow.

Open the calculator

Editorial notes

Worked out by the Snuug team on 12 November 2026 with the same code as the room lighting calculator, so the two cannot disagree. Every rule cites its source, with the date we last checked it. A rule designers use is a convention, not a study.

Other sources the calculator draws on:

  1. Commission Regulation (EU) 2019/2020, equivalence claims for non-directional light sources (470 lm = 40 W, 806 lm = 60 W, 1055 lm = 75 W, 1521 lm = 100 W), checked 31 October 2026
  2. Philips Hue, How far should recessed lights be from the wall? (ceiling height ÷ 2 apart; 50–60 cm from the wall at 2.4 m), checked 31 October 2026
  3. BLT Direct (7 May 2026), What is the difference between warm white, cool white and daylight LEDs?, checked 31 October 2026
AnswersHow many lumens for a living room?A typical living room (4.5 × 3.8 m, 17.1 m²) needs 3,450–6,950 lumens from all its bulbs together, to reach 100–200 lux.AnswersHow high to hang pendant lights over a kitchen island?Hang pendants with the bottom of each shade 80 cm (31 in) above a kitchen island: 170 cm (67 in) from the floor over a worktop 90 cm (35 in) high.GuidesWarm white vs cool white: which bulb for each room?Warm white is 2700–3000 K, cool white about 4000 K, daylight 5000–6500 K. Which bulb lighting shops suggest for each room, and what studies found.